'\" et
.TH TTYNAME "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
ttyname,
ttyname_r
\(em find the pathname of a terminal
.SH SYNOPSIS
.LP
.nf
#include <unistd.h>
.P
char *ttyname(int \fIfildes\fP);
int ttyname_r(int \fIfildes\fP, char *\fIname\fP, size_t \fInamesize\fP);
.fi
.SH DESCRIPTION
The
\fIttyname\fR()
function shall return a pointer to a string containing a null-terminated
pathname of the terminal associated with file descriptor
.IR fildes .
The application shall not modify the string returned. The returned
pointer might be invalidated or the string content might be overwritten
by a subsequent call to
\fIttyname\fR().
The returned pointer and the string content might also be invalidated
if the calling thread is terminated.
.P
The
\fIttyname\fR()
function need not be thread-safe.
.P
The
\fIttyname_r\fR()
function shall store the null-terminated pathname of the terminal
associated with the file descriptor
.IR fildes
in the character array referenced by
.IR name .
The array is
.IR namesize
characters long and should have space for the name and the terminating
null character. The maximum length of the terminal name shall be
{TTY_NAME_MAX}.
.SH "RETURN VALUE"
Upon successful completion,
\fIttyname\fR()
shall return a pointer to a string. Otherwise, a null pointer shall
be returned and
.IR errno
set to indicate the error.
.P
If successful, the
\fIttyname_r\fR()
function shall return zero. Otherwise, an error number shall be
returned to indicate the error.
.SH ERRORS
The
\fIttyname\fR()
function may fail if:
.TP
.BR EBADF
The
.IR fildes
argument is not a valid file descriptor.
.TP
.BR ENOTTY
The file associated with the
.IR fildes
argument is not a terminal.
.P
The
\fIttyname_r\fR()
function may fail if:
.TP
.BR EBADF
The
.IR fildes
argument is not a valid file descriptor.
.TP
.BR ENOTTY
The file associated with the
.IR fildes
argument is not a terminal.
.TP
.BR ERANGE
The value of
.IR namesize
is smaller than the length of the string to be returned including the
terminating null character.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
The term ``terminal'' is used instead of the historical term
``terminal device'' in order to avoid a reference to an undefined
term.
.P
The thread-safe version places the terminal name in a user-supplied
buffer and returns a non-zero value if it fails. The non-thread-safe
version may return the name in a static data area that may be
overwritten by each call.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<unistd.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
